Does this update replace the Cumulative Security Update of ActiveX Kill Bits (2618451)?No, for the purpose of automatic updating, this update does not replace the Cumulative Security Update of ActiveX Kill Bits (2618451) that is described in Microsoft Security Bulletin MS11-090. Automatic updating may still offer the MS11-090 update to customers regardless of whether or not they installed this update (2695962). However, customers who install this update (2695962) do not need to install the MS11-090 update to be protected with all the kill bits set in MS11-090.

Why is Microsoft releasing this Update Rollup for ActiveX Kill Bits with a security advisory when previous kill bit updates were released with a security bulletin?Microsoft is releasing this Update Rollup for ActiveX Kill Bits with an advisory because the new kill bits do not affect Microsoft software.

What is a kill bit?A security feature in Microsoft Internet Explorer makes it possible to prevent an ActiveX control from ever being loaded by the Internet Explorer HTML-rendering engine. This is done by making a registry setting and is referred to as setting the kill bit. After the kill bit is set, the control can never be loaded, even when it is fully installed. Setting the kill bit makes sure that even if a vulnerable component is introduced or is re-introduced to a system, it remains inert and harmless.

Why does this update not contain any binary files?This update only makes changes to the registry to disable the controls from instantiating in Internet Explorer.

Should I install this update if I do not have the affected component installed or use the affected platform?Yes. Installing this update will block the vulnerable control from running in Internet Explorer.

Does this update contain any kill bits that are not Microsoft-specific?Yes. Microsoft has been requested by organizations to set the kill bit for controls that the organizations own and have found to be vulnerable. See the subsection, "Third-Party Kill Bits," in the Vulnerability Information section.

Does this update contain kill bits that were previously released in an Internet Explorer security update?No, this update does not include kill bits that were previously released in an Internet Explorer security update. We recommend that you install the latest Cumulative Security Update for Internet Explorer.

Why does this advisory not have a security rating associated with it?This update contains new kill bits for third-party controls. Microsoft does not provide a security rating for vulnerable third-party controls.

Workarounds

Prevent COM objects from running in Internet Explorer

You can disable attempts to instantiate COM object in Internet Explorer by setting the kill bit for the control in the registry.

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To set the kill bit for a CLSID with value of {B8E73359-3422-4384-8D27-4EA1B4C01232}, paste the following text in a text editor such as Notepad. Then, save the file by using the .reg file name extension.

You can apply this .reg file to individual systems by double-clicking it. You can also apply it across domains by using Group Policy. For more information about Group Policy, see the TechNet article Group Policy collection.

Note You must restart Internet Explorer for your changes to take effect.

Impact of Workaround. There is no impact as long as the object is not intended to be used in Internet Explorer.

How to undo the workaround. Delete the registry keys previously added in implementing this workaround.

Disclaimer

The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.